Management of systemic hypertension in dogs and cats

Sakan / stock.adobe.com

Systemic hypertension, or sustained elevations in systemic blood pressure over 160 mmHg, can occur in veterinary patients. Screening for hypertension is recommended in cats and dogs over 9 years of age, during triage for ill patients, and in patients with a primary disease that predisposes them to secondary hypertension, such as chronic kidney disease, Cushing’s disease, hyperthyroidism, and hyperaldosteronism.

“The reason we care about high blood pressure is that it’s something that potentially puts our patients at risk for adverse outcomes or could potentially cause a decrease in quality of life,” says Michael Hickey, DVM, DACVIM (cardiology), of CVCA-Cardiac Care for Pets. During a session at the recent 2022 AVMA Convention, Hickey discussed the diagnosis and management of systemic hypertension in canine and feline patients.

Diagnosing hypertension

Blood pressure can be measured indirectly by Doppler or oscillometric blood pressure machine. Doppler measurements are generally preferred as they are more hands on and allow for more quality control. Oscillometric blood pressure units are convenient but are validated in anesthetized animals, making their use in awake animals less reliable.

Veterinarians should interpret blood pressure measurements with caution as the stress of being in the clinic can influence blood pressure measurements and create a situational hypertension. “That’s the bane of our practice,” said Hickey. “We’re in a situation that is probably really stressful for the patients that we see, so it can be difficult to establish a reliable diagnosis in some pets.” In pets without clinical signs of hypertension—such as lethargy, bradycardia, epistaxis, or signs of target organ damage in the eyes, brain, heart, or kidneys—multiple blood pressure measurements should be obtained over time to best determine if a pet is truly hypertensive.

Hickey shared several tips for best practices in blood pressure measurement, including:

• Creation of a standardized procedure for how blood pressure measurements are obtained in your clinic.
• Use a quiet, isolated room away from other patients, such as an examination room.
• Consider having the owner present as this may reduce the influence of stress on blood pressure
• Always use a trained and experienced operator, such as an experienced veterinary nurse.
• Gently restrain the patient in lateral or ventral recumbency to keep the patient calm and motionless.
• The cuff should be placed on the distal limb or tail in line with the level of the heart base.
• Multiple measurements should be taken. The first should be discarded and five to seven consistent measurements should be averaged. If the blood pressure is trending down, wait until it plateaus to record the measurements.

Blood pressure can be classified as normotensive, pre-hypertensive, hypertensive, or severely hypertensive, according to the ACVIM Consensus Guidelines, which were last updated in 2018.¹ Each level of hypertension has an associated risk for target organ damage (see table 1). “The risk of target organ damage is why we pursue treatment,” said Hickey.

Treatment of systemic hypertension

Determining when treatment should be instituted is an important decision that should be made based on the presence of target organ damage and serial blood pressure measurements. “It’s not just that we’re starting a medication that can have side effects,” said Hickey. “We’re also starting a medication that, once you start it, your intention is to continue this medication for the rest of the pet’s life. That’s a pretty big ask for the pet’s family.”

For patients with blood pressure levels in the normotensive to pre-hypertensive zones on screening, continued monitoring should be performed every 3 to 6 months depending on patient risk factors including age and presence of a predisposing disease.

For patients presenting with clinical signs of target organ damage and a blood pressure over 160 mmHg, treatment should be instituted immediately and further diagnostics to investigate for an underlying disease should be pursued.

Treatment is not started after a single blood pressure measurement over 160 mmHg if there is no target organ damage present. However, patients should be monitored closely for development of target organ damage and blood pressure measurements should be repeated. For patients classified as hypertensive (BP 160-179 mmHg), BP measurements should be repeated twice over an 8-week period. Patients with severe hypertension should be more closely monitored and have BP measurements repeated twice over a 2-week period. Patients with repeatably elevated BP should be treated and investigated for underlying disease.

There are three main classes of drugs used for treatment of hypertension: ace-inhibitors, angiotensin-receptor blockers (ARBs), and calcium channel blockers. Ace-inhibitors and ARBs are advantageous for patients with proteinuria. In dogs, ACE-inhibitors are the first line treatment. In severe or refractory cases, amlodipine is added. In cats, amlodipine is the preferred first-line treatment. ARBs or ACE-inhibitors are added in severe or refractory cases. There are some exceptions to these treatment plans in cases of pheochromocytoma and hyperaldosteronism. Any underlying disease that predisposes a pet to hypertension should also be treated.

Patients should be monitored frequently until controlled, starting as early as 1-3 days following institution of treatment. The target blood pressure is ideally below 140 mmHg, but 160 mmHg may be acceptable for some patients. For patients with concurrent proteinuria, target levels are less than 50% the level at presentation. Once blood pressure is controlled in the target range on medication, monitoring should be performed every 3-6 months.

Take home points

Systemic hypertension poses serious risks of ocular, neurologic, cardiovascular, and renal damage for veterinary patients. Obtaining consistent, reliable blood pressure readings should be a priority for veterinary teams. Patients with target organ damage and hypertension should be treated immediately. In the absence of target organ damage, treatment should be withheld until hypertension has been repeatedly documented. All patients receiving treatment for systemic hypertension should be closely monitored.

Reference

Acierno MJ, Brown S, Coleman AE, et al. ACVIM consensus statement: Guidelines for the identification, evaluation, and management of systemic hypertension in dogs and cats. J Vet Int Med. 2018;32(6):1803-1822. https://doi.org/10.1111/jvim.15331

Dr. Boatright, a 2013 graduate of the University of Pennsylvania, is a practicing veterinarian and freelance speaker and author in western Pennsylvania. She is passionate about mentorship, education, and addressing common sources of stress for veterinary teams and recent graduates. Outside of clinical practice, Dr. Boatright is actively involved in organized veterinary medicine at the local, state, and national levels.